Field of the Invention
The present invention relates to a tubular heat exchanger, and more particularly, to a tubular heat exchanger which includes tubes, each having a plurality of cells inside, stacked in multiple stages and zigzag-bent heat-radiating fins brazed and integrated among the tubes, wherein gaps among the tubes become progressively wider toward the rear to enable foreign substance to immediately be discharged without being caught by the heat-radiating fins, and an air-cooling performance at a tube surface is not degraded even if the rear gaps among the tubes become wider.
Background of the Related Art
An air-cooled type tubular heat exchanger, used in a radiator or an air conditioner of a vehicle, is an apparatus which conducts heat toward air in a process, wherein high-temperature fluid is moved, in order to lower the temperature of fluid or refrigerant.
FIG. 1 is a conventional tubular heat exchanger having tubes 11, through which fluid is moved, connected in multiple stages between a header pipe 21 and the other header pipe 21′, and corrugated heat-radiating fins 15 of thin metallic material for heat radiation attached among the tubes 11 with a brazing method, wherein high-temperature fluid supplied to the header pipe 21 through a supply duct 22 is distributed through the tubes 11 to be discharged to a discharge duct 23 through the other header pipe 21′, and air blown by operation of a blower fan 24 passes among the corrugated heat-radiating fins 15 attached among the tubes 11 at the same time. Here, the hot air of the high-temperature fluid is cooled by wind through the tubes 11 and the heat-radiating fins 15.
As in FIG. 2, a cross-section of the conventional tubes 11 disclosed in Kor. Pat. No. 518856 is a rectangular shape, wherein cells 13 divided by a plurality of partition walls 12 are formed inside, and the corrugated fins 15 of metallic material are attached on upper and lower surfaces of the tubes 11 to be used. However, the tubes 11 for a heat exchanger cause the following problems.
The upper and lower surfaces of the tubes 11 are horizontally formed, and the width of a front end and the width of a rear end are equal, causing foreign substance 31 to easily be accumulated and fixed, thereby lowering heat exchange efficiency due to the foreign substance 31. To prevent the foreign substance 31 from easily being accumulated in the tubes 11, the tubes 11 may be formed in an oval shape as in FIG. 3 to enable the foreign substance 31 to naturally be flowed downward. However, if the tubes 11 are formed in the oval shape, surfaces of the corrugated fins 15 coming in contact with surfaces of the tubes 11 also have to be formed in a curved line, thereby making the manufacturing process of the corrugated fins 15 complex and lowering productivity. Also, a central portion among the tubes is narrow, thereby causing a bottleneck phenomenon if foreign substance is stuck.
A technology, wherein a front end of a tube is narrower than a rear end of the tube to enable gaps among the tubes become narrower toward the rear, is suggested by Jap. Pat. No. 20-241057. This is to reduce airflow resistance. The gaps among the tubes become narrower from the front to the rear in order to initially reduce the airflow resistance when wind from a blower fan passes among the tubes, and to enable moisture to be dropped by tilting front portions of the tubes downward if the moisture is formed on the tube surfaces.
Although the airflow resistance is reduced, the rear gaps among the tubes become relatively narrower, thereby causing foreign substance to be accumulated in the rear gaps among the tubes if the heat exchanger is used as an outdoor unit in the Middle East where a sandstorm frequently occurs or in China where the yellow dust severely occurs.
Also, a technology, wherein a front end of a tube is thicker than a rear end of the tube to enable the foreign substance to naturally be discharged, is suggested by Jap. Pat. No. 14-139282.
However, the thick front end of the tube cause the front gaps among the tubes become relatively narrower than the rear gaps, thereby generating airflow resistance. The upper and lower surfaces of the tubes are formed in a streamlined shape, thereby causing a difficulty of manufacturing a groove of a cooling plate in the streamlined shape. Particularly, the cooling plate is formed by arranging a vertically-stood single plate, thereby occupying a relatively greater area than a cooling fin, shortened by being zigzag-bent, to enlarge a heat-radiating area, and being impossible to be used in a narrow installation space due to the cooling plate protruded toward the rear by being deviated from a rear portion of the tube.